It happens because there isn't enough variety in your tag cloud (they all have the same occurrences). As soon as one tag occurs more than the rest, the error will go away. I'll fix that for next release.
First I've heard of such an issue, never seen it myself. It's certainly not intentional, but I can't say much more than that at this point. What version of IPB? How are you moving them? If you run a search reindex, does that fix it?
Fine idea, but I'm trying to keep everything app-agnostic. I couldn't add that without making it completely Forum-specific. Doing that for every prefix-capable app in turn is not very practical.
Not yet.
This is a known bug, see numerous replies on the last page. Until it's fixed, you can temporarily disable AT&P to make any Pages settings changes.
Yes.
No, it is not "just a sorting thing".
I'm not sure I understand. Are you saying, since the search engine already incorporates tags and forums, it should be easy? ...No, the search engine functionality would not help with filtering and sorting a forum. I'm not about to rewrite a fundamental part of the Forum application.